package com.ihr360.job.core.repeat;

/**
 * Interface for listeners to the batch process. Implementers can provide
 * enhance the behaviour of a batch in small cross-cutting modules. The
 * framework provides callbacks at key points in the processing.
 *
 * @author Dave Syer
 *
 */
public interface RepeatListener {
    /**
     * Called by the framework before each batch item. Implementers can halt a
     * batch by setting the complete flag on the context.
     *
     * @param context the current batch context.
     */
    void before(RepeatContext context);

    /**
     * Called by the framework after each item has been processed, unless the
     * item processing results in an exception. This method is called as soon as
     * the result is known.
     *
     * @param context the current batch context
     * @param result the result of the callback
     */
    void after(RepeatContext context, RepeatStatus result);

    /**
     * Called once at the start of a complete batch, before any items are
     * processed. Implementers can use this method to acquire any resources that
     * might be needed during processing. Implementers can halt the current
     * operation by setting the complete flag on the context. To halt all
     * enclosing batches (the whole job), the would need to use the parent
     * context (recursively).
     *
     * @param context the current batch context
     */
    void open(RepeatContext context);

    /**
     * Called when a repeat callback fails by throwing an exception. There will
     * be one call to this method for each exception thrown during a repeat
     * operation (e.g. a chunk).<br>
     *
     * There is no need to re-throw the exception here - that will be done by
     * the enclosing framework.
     *
     * @param context the current batch context
     * @param e the error that was encountered in an item callback.
     */
    void onError(RepeatContext context, Throwable e);

    /**
     * Called once at the end of a complete batch, after normal or abnormal
     * completion (i.e. even after an exception). Implementers can use this
     * method to clean up any resources.
     *
     * @param context the current batch context.
     */
    void close(RepeatContext context);
}